In order to ensure the safety of secret information, a person and the like which exist inside an area such as a particular room, a building and the like, an idea is typically executed that the person who can pass through an entrance and a path to a particular area is limited to the person who is preliminarily permitted to pass (hereinafter referred to as a pass permitted person). For example, in order to limit the person who can enter a room in which secret information is handled for the sake of secret protection in a corporation and the like, the person who can pass through an entrance of the room is limited. In order to ensure the safety of residents in a complex housing such as a condominium building or the like, the persons except the residents are limited to enter an entrance of the condominium building. The judgment of the pass permission or pass unpermission can be executed based on: evidence indicating pass permission such as an IC card, information known by only the person having the pass permission such as a personal identification number, and, biometrics authentication such as a finger print and a face. The person who can enter the area can be limited by using a door and gate that can be opened by the person permitted to pass in advance.
However, even if the limitation is carried out by opening and closing a door, there is a problem of so-called tailgating in which, when a pass permitted person opens the door, a person who is not permitted to pass (hereinafter referred to as a pass unpermitted person) passes together with the pass permitted person.
An apparatus for avoiding the tailgating is described in Japanese Laid-Open Patent Application JP-P 2005-316787A. In a gate apparatus described in JP-P 2005-316787A, a door that is opened and closed at an interval corresponding to one person is placed, thereby enabling only one person to surely pass and consequently avoiding the tailgating.
Also, another apparatus for avoiding the tailgating is described in Japanese Laid-Open Patent Application JP-P 2006-120086A and Japanese Laid-Open Patent Application JP-P 2006-236183A. In a tailgating detecting system described in JP-P 2006-120086A, visitors are imaged by a camera and the number of the visitors is counted. Then, when the number of the visitors exceeds the number of the persons who carry out action for unlocking a key, a warning message is announced from a speaker placed at an entrance so that the tailgating is avoided. Also, in an entrance and exit managing system described in JP-P 2006-236183A, an RFID tag is given to the person who is allowed to enter, and a video picture in front of a door and information from an RFID reader are combined. Consequently, the door is opened only for the pass permitted person.
On the other hand, as a method of ensuring the safety of a particular area by using a method except the method of limiting a person to be permitted to enter the area, there is a method of detecting an unpermitted invader from a video picture of a monitoring camera. The monitoring camera is placed at a place from which the particular area can be observed, and an observer observes the video picture of the camera and consequently detects the invader. For example, in an invasion material monitoring apparatus described in Japanese Laid-Open Patent Application JP-A-Heisei 07-288802, an invader is automatically detected, and a video picture of the invader is enlarged and projected on a monitoring monitor. Thus, a load of the observer is reduced.
In the method described in JP-P 2005-316787A, the entering action is limited by using the door that is opened and closed at the interval corresponding to one person so that only one person can enter at the same time. Thus, the person is required to act based on the opening and closing interval of the door that is finely controlled, and the action is limited. It takes long time as compared with usual entering action. Convenience is especially dropped when many persons pass simultaneously through an entrance of a corporation just before a business start. Moreover, when a person has a burden or has a body bigger than an assumed interval, there is a possibility that it is difficult for the person to pass. Also, when it is placed at an entrance of a condominium building or the like, a family including at least a parent and a child cannot enter the entrance altogether. That is, when only one person is permitted to enter the entrance at a time, there is a possibility that availability is extremely dropped. Moreover, if a gate is closed to avoid a pass unpermitted person from entering the entrance when the pass unpermitted person tries to pass, a pass permitted person, who tries to pass following the pass unpermitted person, cannot pass. Thus, this hinders the pass permitted person from passing. Also, in the methods described in JP-P 2006-120086A and JP-P 2006-236183A, when the pass unpermitted person who is not permitted to enter the room is located in front of the door, the warning is announced, or the door is not opened, thereby trying to avoid the invasion of the pass unpermitted person. For this reason, even in a case that both of the person who is permitted to enter the room and the person who tries the invasion by using the tailgating are located in front of the door, the warning is announced or the door is not opened. Thus, until the pass unpermitted person disappears, the pass permitted person also receives the warning or waits for the opening of the door. Hence, the pass permitted person is handled similarly to the invader.
If the foregoing conventional techniques are used to avoid the tailgating, the convenience when the pass permitted person passes is extremely dropped. This is because as mentioned above, in order to avoid the invader (pass unpermitted person) who tries an invasion by using the tailgating from entering the entrance, persons including the pass permitted person must be blocked not to pass by using the method that simultaneous passing of two persons is limited or the door is not opened when the invader exists near the pass permitted person.
On the other hand, in the method of ensuring the safety of a particular area by using the method except the method of limiting an enterable person, the convenience of the pass permitted person of the gate is not lost. However, it is important to avoid the invader (pass unpermitted person) from performing fraudulent activities after the invasion. The invasion material monitoring apparatus described in JP-A-Heisei 07-288802 automatically detects the invader, enlarges and projects the video picture of the invader on the monitoring monitor and consequently reduces the load of the observer. However, all of handling manners against invaders are entrusted to judgment of the observer itself. Thus, there is a possibility that the judgment error of the observer or the like leads to an unanticipated result. In particular, if the place where contact with the invader occurs (for example, the place from which the warning is announced for the invader, or the place at which the invader is caught: hereinafter referred to as a handling place) is suitably selected, there is a possibility that the convenience of the pass permitted person is lost or valuable articles inside the monitored area is broken.